Abstract

The Bula Basin is an arcuate Late Tertiary to Quaternary sedimentary basin occurring both onshore and offshore along the north-eastern flank of the Island of Seram in eastern Indonesia. It covers a land area of approximately 800 km² with an axial length of about 80 km.

Sedimentation began in the Early Pliocene with a marine transgression that continued into the Early Pleistocene and resulted in deposition of bathyal facies mudstone and siltstone in the deeper parts of the Basin. In the Early Pleistocene uplift occured resulting in the formation of a regional unconformity in the sedimentary sequence. This uplift was followed by further transgression and deposition of neritic sediments during Pleistocene to Recent times. The estimated maximum thickness of sediments in the Basin is 1400 m.

The Bula Basin is a proven petroliferous basin with the stratigraphic Bula Oilfield of Pleistocene age on its north-western margin. In addition abundant surface oil seeps are present along the western margin of the Basin near the basement outcrop in the Bula and Belien-Kola areas. The prolific nature of these oil seeps together with the knowledge of porous beach and bar sand and reefal limestone in the subsurface within the onlapping Pleistocene sediments indicates that future exploration within the Bula Basin has good prospects of discovering additional fields.